ARS | Publication request: DOWNSTREAM VERSUS UPSTREAM EFFECTS OF CONSERVATION PRACTICES

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: November 4, 2004
Publication Date: November 4, 2004
Citation: Franklin, D.H., Cabrera, M.L., Steiner, J.L., Risse, L.M., Gaskin, J. 2004. Downstream versus upstream effects of conservation practices. American Society of Agronomy Meetings.

Technical Abstract: The degree of impact imposed by conservation practices to reduce nutrient contamination to aquatic systems, though critical, is not easy to measure because it is dependent upon the endpoint in question, scale, and watershed morphology. The objectives of this work were to evaluate the spatial distribution of stream base flow nutrients (nitrogen & phosphorus) at watershed and farm levels as affected by management, and to increase awareness of participatory research. Presented results were gathered from 20 farms from Dec. 1998 to Feb. 2002. Crop systems are shown to be significantly lower (p < 0.05) exporters of dissolved reactive phosphorus (DRP) and nitrate (NO3-N) in stream base flow than hay or pasture systems when collecting downstream of management systems (watershed scale). In contrast, when downstream dissolved nutrient concentrations were subtracted from upstream concentrations (farm scale) no significant differences (p < 0.05) in NO3-N stream base flow concentrations are indicated and haying systems had the lowest stream base flow concentrations of DRP. Contrasting results between farm scale and watershed scale indicate that scale can greatly influence the interpretation of impact imposed by conservation practices and variability identified at the farm scale should be maintained when scaling up to watershed scale.